A Theoretical and Computational Analysis of the Methyl-Vinyl + O2 Reaction and Its Effects on Propene Combustion

A detailed analysis of the reaction of CH 3 CCH 2 and CH 3 CHCH with molecular oxygen is presented. The C 3 H 5 O 2 potential energy surface was characterized using a combination of electronic structure methods. The majority of the stationary points on the PES was determined at the CCSD(T)-F12a/cc-pVTZ-F12//B2PLYPD3/cc-pVTZ level of theory, with the remaining transition states computed using multireference methods. Microcanonical rate theory and the master equation are used to determine the temperature- and pressure-dependent rate coefficients for each reaction channel. The main product channels are CH 2 O + CH 3 CO for CH 3 CCH 2 and CH3CHO + CHO for CH 3 CHCH. The rate constants for these two reactions at 1 atm are k = 9.03 × 10 22 × T –3.21 × exp –2162/ T and 1.50 × 10 19 × T –2.10 × exp –1260/ T cm –3 mol –1 s –1, respectively. In contrast to C 2 H 3 + O 2, the methyl-vinyl + O 2 reactions remain chain propagating, even at high temperatures. The new rate coefficients were implemented in a detailed mechanism taken from the literature. These changes have a modest effect on the ignition delay time and laminar flame speeds for propene combustion.